This invention relates to an air damper for an open fireplace of the type, at which heat exchange takes place between the heat generated in the fireplace and cooler air, and where said air in heated state is intended to be transported via a distribution system to one or several rooms to be heated.
In order to increase their efficiency degree, open fireplaces of different types have been provided with heat exchangers for the heating of air, which has a temperature lower than the desired room temperature. Distribution systems, furthermore, have been developed to transport the heated air to other rooms than the one where the fireplace is located, in order to heat said rooms. In apartments, thus, the heated air is passed through a ventilation system from fireplaces to the other rooms.
The highest efficiency degree of an open fireplace knowingly is obtained when the air to be heated is passed through the heat exchanger of the fireplace by means of a fan, preferably an electric one, whereby desired air amounts can be passed through the heat exchanger.
An open fireplace, which is dimensioned to be fan-operated and thereby to produce the maximum heating effect within the margins of reasonable safety with respect to air temperature in the distribution system, delivers air of a temperature preferably slightly below 80.degree. C. In Sweden, the air temperature in the distribution passages is by regulations limited to 80.degree. C. at maximum. In the event of current interruption during operation, however, with resulting shut-off of the fan, the air temperature increases very rapidly because the air flow through the heat exchanger is stopped. Due to the fact, that a highest permissible air temperature in the distribution passages (in Sweden 80.degree. C.) during operation cannot be guaranteed, open fireplaces of the type here concerned could not be utilized to such an extent as motivated a.o. by its advantages with respect to fuel costs and high efficiency degree.
The present invention solves the aforesaid problems. It relates to an air damper for an open fireplace, which is designed so that heat exchange takes place between the heat generated in the fireplace and cooler air, which is passed through the fireplace by an electric fan and in heated state is transported in distribution passages to one or several rooms to be heated.
The invention is characterized in that the damper is positioned on the hot air side of said heat exchanger, and that the device comprises a rotatable metal sheet or the like constituting a damper, which is capable to assume a first and a second end position, and the damper in said second end position prevents the air stream from passing to the distribution passages and permits the air stream to pass on to the room where the open fireplace is located or into a space safe for high temperatures, and the damper in said first end position permits the air stream to pass out into the distribution passages and prevents the air stream from passing out into said lastmentioned room, and that the damper is adapted by action of a force to assume said second end position when there is risk of excess temperature in the distribution passages, which force arises when the function of said fan is disturbed so that the air temperatures in the device exceed a predetermined value.